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Fair Value Measurements - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Cash equivalents maturity period, days	90 days

X

- Definition

Short term deposits maximum maturity period.

+ References

No definition available.

+ Details

Name:	tdw_ShortTermDepositsMaximumMaturityPeriod
Namespace Prefix:	tdw_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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- References

No definition available.

+ Details

Name:	us-gaap_FairValueDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration